Water-resistant polyhydric alcohol-carboxylic-acid resin and process of making same



Patented Apr. 24, 1928. 1

UNITED STATES PATENT OFFICE.

CHARLES R. DOWNS, OF CLIFFSIDE, AND LOUIS WEISBERG, OF GRANTWOOD, NEW JERSEY, ASSIGNORS TO THE BARRETT COMPANY, A CORPORATION OF NEW JERSEY.

WATER-RESISTANT POLYHYDRIC ALCOHOL-CARBOXYLIC-ACID RESIN AND PROCESS OF MAKING SAME.

No Drawing.

Rcsinous materials of widely difl'erent properties have heretofore been made from glycerol by suitable combination thereof with a dibasic aromatic acid alone, a dibasic aliphatic acid alone and also with a mixture of varying proportions of both an aromatic dibasic and an aliphatic dibasic acid. See U. S. Patents: 1,082,106, Dec. 23, 1913; 1.9914327. Mar. 31, 191-1; 1,091,628, Mar. 31, 1914; 1,991,732, Mar. 31, 1911; 1,098,728, June 2. 1914; 1,098,776, June 2, 191-1; 1.098.777. June 2, 1914; 1,108,329, Aug. 25, 1911; 1,108.330, Aug. 25, 1914; 1,108,331, Aug. 2:) 1914; 1,108,332, Aug. 25, 1914; 1,119.592, Dec. 1, 1914.

In the case of those materials from glyccrol and phthalic acid (an anhydride-torm- 111g aromatic dibasic acid) alonc'this combination has been observed to pass through three stages, a first solid stage (the A-stage), a second solid stage (the B-stage) and a third solid stage (the C-stage). The ultimate industrial utility of these resinous products lies in their use in molding and like compositions. For this the above-described C-stage product is very superior to the corresponding B-stage product and can be used successfully in a large number of cases where the B-stagc product is useless.

In the case of those materials from glycerol and a dibasic aliphatic acid or a mixture of dibasic aliphatic acid and an anhydridcforming dibasic aromatic acid, a solid product other than that corresponding to the B-stagc product of the glycerol-aromatic dibasic acid group has never been described or indicated, although such B-stage products have themselves been known for many years.

Yew, it remained for us to discover that these relatively useless B-stage products can be converted into very useful and highly desirable products which are then among the very best insulating materials available to the industries.

In addition we have also discovered that useful C-stage products can be made from the less useful B-stage products resulting 1' mm glycerol and a polynuelear aromatic acid, such as diphenic acid, 1.8-naphthalic acid, bcnzoyl benzoic acid, methyl-benzoyl hcnzoic acid and chlor-benzoyl benzoic acid, and an aliphatic dibasic acid. Furthermore, we have also discovered that a tribasic ali- Application filed December 22, 1920. Serial No. 432,408.

phatic acid, such as citric acid and malomalic acid, can be employed in place of dibasic aliphatic acids in producing useful C-stage products either alone or in mixture with the above-named aromatic acids.

In converting these relatively useless B- stagc products into our new products, we have thereby caused the latter to retain substantially all of the elasticity and flexibility of the B-stage products from which they are respectively made, while we have at the same time increased the electrical insulating properties of our new products beyond that of the corresponding B-stage products. These changes, alone or together, would no add to the utility of the B-stage products in any substantial manner. However, our new products do difi'er from the B-stage products from which they are respectively derived in one most essential particular and the one which enables our new products to be used under circumstances where the corresponding B-stage products cannot be employed at all. These B-stage products are all decomposed or so altered by water that they cannot be employed in places where water contact is unavoidable such as in submarine cables or in exterior and openly exposed positions where they are subject to action of dew, rain, snow or frost. The B-stage products under these conditions become soft or s ongy or porous. lose in elasticity and flexibility and also lose in cohesiveness, resistance to shock, friction and to the passage of electric current. while our new products suffer no material change in any or all of these respects through such water contact, while at the same time they can equally well be employed in any and all other uses to which these B-stage products have been successfully put.

To effect this change of the old B-stage products above referred to into our new products, we apply prolonged and high heating to these B-stage products until the change to our new products has been satisfactorily effected. In general, this is the same means employed to convert the B-stage products of the glycerol-phthalic acid resin into the corresponding C-stage product. (See U. S. Patent 1,108,330, August 25, 1914.)

In general, these A-stage products we operate with are hard without being stiekyis the subject of U. S. Patent 1,108,330 of and are fusible; upon proper heating these A-stage products all become infusible and reach the B-stage which B-stage products, 5 when submerged in boiling distilled water, become coated with a bloom, always in less than two minutes; these B-stage products when further properly heated remain infusible but lose the above described sensitiveness to water when the C-stage has been reached. These properties are so sharp and so characteristic that an operator can, with certainty, determine when he has arrived at each of these three stages, when making these materials in bulk.

We have employed the following polybasic aliphatic acids; among the dibasic acids we have emplo ed and found useful are the following: umaric acid; maleic acid; malic acid; succinic acid and tartaric acid; amon the tribasic acids we have employed an follld useful are citirc acid and malo-malic aci We have employed the following mixtures of the foregoin as well as others not mentioned below. he figures in the table represent the molecular proportions of each acid used.

Suceinic 'Inrtm-ie acid acid "ifii 1.0 1.0

Accordingly, the expression phthalic acid as used above and hereinafter, when not otherwise specified or indicated, is intended to designate both the acid as such or its 5 equivalent anhydride.

We have emplo ed phthalic acid, an aromatic dibasic aci both as such, and as its anhydride, in mixture with the foregoing dibasie aliphatic acids, as shown, for example, in the following table:

N0 Phthalic Fun aric Malelc Malia Suecinic Tartarie acid acid acid acid acid ac i 1.0 2 1.5 a 0.5 4 1.0 5 L5 6 0.5 7 u 1.0 s 1.0 o 1.0

We have employed glycerol, glycol, digl c erol and triglycerol, all of which are polyhydric alcohols or polyhydric alcoholic bodies. We make no claim to a resin made 55 from phthalie anhydride alone because this August 25, 1914. We have discovered, however, that diphenic acid, 1.8-naphthalic acid and the benzoyl benzoic acids form with the above-mentioned alcohols resins which are unalfected by water and we herein claim these resins as part of our invention. Of the various benzoyl benzoic acidi we have used benzoyl benzoic acid, methyl-benzoyl henzoio acid and (-hlor-henzoyl licnzoic acid, which we made by condensation of phthalic anhydride with benzol, toluol and chlor-benzol respectively in the presence of aluminum chloride, in the manner well known to chemists and have obtained satisfactory resins.

Benzoyl benzoic acid is represented by the following formula, to wit:

We have also made resins with each of these aromatic acids mixed with one or more of the previously mentioned polybasic aliphatic acids and have obtained satisfactory and useful results.

PuonUoiNo THESE PRODUCTS IN BULK.

Emample IPart A. A wmge resin from glycerol and malcic acid.Heat together quantities of glycerol and maleic acid in the proportion of one molecular weight of glycerol to one molecular weight of acid. The acid dissolves, forming a homogeneous mass. As the heating is continued, the melting point gradually rises, and the material, which at first is quite sticky and viscous, eventually loses its stickiness and becomes more solid when cold. The completion of the first reaction can be ascertained by taking outa small sample, and allowing it to cool. If the cooled product is viscous or tenacious but not sticky, the reaction has gone far enough. At this stage the product is soluble in acetone, makin a clear solution useful as a varnish. By t is time the melting oint is usually over C. and may be as iigh as C. (melting points taken by the method described on gage 821, vol. 10, Journal of Industrial and ngineering Chemistry). The time required to reach this point may vary according to he temperature at which the heating is conducted, the bulk of the material emgloyed, and the rate of stirring. It is selom advanta eous to let this temperature exceed 200 (i, as it is then difficult to control the next step in the reaction. On the other hand, it is desirable to keep the temperature as high as possible (i. e. as near 200 C. as possible; because the reaction otherwise proceeds s owly. For example, a batch of two pounds may be converted at C. in approximately 20 hours. If the material is cooled before the next stage of the reaction sets in, the product obtained is fusible and soluble in cold acetone. This resin is also soluble at room temperature in ethyl alcohol and ethyl acetate although not so much as in acetone. It dissolves slightly in benzene. Cold water acts on it rapidly, causing it to become discolored and soft.

E trample [Part B.

B-stage resin. from glycerol and maicic (mitt-Heat the product of Example 1- Part A until a specimen on suitable test shows that it is no longer fusible, that it is insoluble in cold acetone, and also that it is affected when suluuerged in boiling distilled water for two minutes. The temperature of heating may be as high as in Part A, but in that case the reaction becomes violent, frothing and evolution of heat take place, and the material becomes filled with bubbles. This frothy product may be rendered homogeneous by connninuting it and then molding it under heat and pressure. A bubble-free product may be obtained directly, however, by heating at a temperature properly at or near the melting point of the A-stage resin; the maximum temperature should not be above about 135 C. and the temperature may be as low as 90 C. or lower. By which ever method it is obtained, the resin is infusible and has no true melting point, although it softens sufficiently to be molded under heat and pressure. It is insoluble in acetone, ethyl alcohol, and ethyl acetate, but on standing, in contact with any of these materials for a considerable time, the finely powdered resin swells and forms a sort of jelly-like mass. For example, a batch of two pounds may be converted at 135 C. in about ten hours from the A-stage resin to the B- stage resin.

Ewamplc IPa7't U.

U-stage resin from glycerol and maleic acid-Heat the product from Example I Part B to a temperature of 170200 C. until a test specimen when submerged for two minutes in boiling distilled water does not show a bloom on its surface. The time required to accomplish this change depends on the temperature used and on the bulk of the material heated. With a large bulk of resin it is important at first not to raise the temperature too rapidly, for the resin is not a good conductor of heat and considerable time is required to equalize the temperature. The final temperature may be as high as 250 C. when time is important. For example, a batch of two pounds may be converted at 170 0.. in approximately 30 hours.

In place of maleic acid of Example I, we have used the followingmalic acid, fumaric acid, succinic acid, and malo malic acid, and with satisfactory results. Moreover, we have used various mixtures of these acids as well as mixtures containing one or moge of these acids together with phthalic aci These final C-stage products are insoluble at room temperature in the following solvents: acetone, ethyl alcohol, benzene, ethyl acetate, chloroform, turpentine, ether, linseed oil, China wood oil, and petroleum transformer oil. They are infusible but soften sufficiently at temperatures above 140 C. to be molded under pressure. Mechanically, electrically, and chemically, these new products are superior to the A and B-stage products from which they are derived. Thus they are hard, tough, elastic, and well suited to the ordinary machining operations. They are resistant to heat, although they burn when put in a flame. The insulating value of the C-stage resins is considerably higher than that of the respective B-stage resins from which they are derived. The new products, moreover, are resistant to cold and to boiling water. Prolonged contact with cold water does not diminish the luster or polish of the surface, and the water remains neutral to litmus. They are substantially unattached at room temperature by 20% solutions of sulphuric, hydrochloric, nitric, or acetic acid, but they will not withstand concentratcd sulphuric acid or hot concentrated nitric acid. They are not materially attacked within one hour by a 20% solution of caustic soda at the ordinary room temperature. However, on boiling in contact with this solution, the resins are decomposed, forming alcohols and sodium salts corresponding or related to the alcohols and acids used in their manufacture.

'While these new C-resins can be used as such for certain purposes, the best, most convenient and practical method of manufacture is to apply the final heat treatment. at the place or in the form of their ultimate use. This is particularly the case when fillers are to be incorporated with the resin, as it is often more convenient to compound the resin and fillers before the final heat treatment is applied.

For example, the finished C-resin may be finely ground, mixed with a suitable filler if desired, and molded by the application of heat and pressure in the wav usual in such operations. We have found that we can employ not only the more expensive kinds of fillers. such as fibrous asbestos, cotton. wood pulp and the like. which have some mechanical strength of their own. but also the cheaper non-fibrous filler, such as talc. rotten stone, wood flour. ground asbestos and other like inertpowdcry materials having no special mechanical strength of their own.

Example I].

Producing a molded article containing U-resin from the Erwin-The B-resin and V has thus reached the B-stage.

the filler, or fillers, are round separately and then thoroughly mixed in the way usual in such operations. All the materials must be finely ground to produce an even mixture. The relative proportions of resin and filler will naturally vary according to the particular pur ose for which the molding composition is lntended. The mixture thus pro duced may be molded under heat and pressure, and the final heat treatment, as in Exam le I-Part C, then applied with the mo ded object still in the mold, or the heat treatment may be applied first and the composition then molded. It is not always necessary to carry out the entire heat treatment in the mold, and the molded object may be removed as soon as it has attained suflicient rigidity to maintain its roper form under further heating, thus re easing the mold for further use and consequently cheapening the process.

Emomple III.

Producing a molded article containing G-resz'n from the B-resin.The B-resin is finely ground and allowed to stand in contact with acetone for a considerable time. The powdered resin swells and forms a jelly-like mass, which is also a suitable form for compounding with a large proportion of filler by kneading or passing between rolls in the usual way in such operations. The composition thus produced is heated to drive ofl' any excess of solvent and may then be handled as in the preceding example. Alternatively, the composition may be molded before driving off the solvent, and the solvent may then be driven off while the object is still in the mold.

Example IV.

Producing a. molded article containing 0'- resin from the A-resin.-The A-resin is melted and the finely ground filler added thereto. The mixture is thoroughly stirred and heated until it becomes infusible and Heating is continued beyond this point as in Example I, to the C-stage; the composition is then ground and molded under heat and pressure in the usual way. Alternatively, the composition is heated only to the B-stage and is then molded and treated as under Example II.

In making a C-stage resin which is to be molded or a molding composition containing a C-stage resin, it is not necessary to complete the heat treatment entirely before the molding operation is carried out. but the heat treatment may be interrupted at such a stage that the heat applied in the subsequent molding operation suflices to produce a finished C-stage product.

Gur new products can be distinguished with certainty from all other heretofore known products by making the following two tests:

I. Place a specimen thereof in boiling distilled water; if its surface remains bright and does not become dull in two minutes, it is water-resistant in the sense we have herein used and will hereafter use that expression.

II. Boil a specimen, say 1 gram, with ten times its bulk of a 20% solution of caustic soda in water until all or nearly all has gone into solution; filter; cool; acidify with hydrochloric acid. From the product of these operations tartaric acid, fumaric acid or succinic acid can all be recovered as such by means usual with chemists for such purposes, from such resins in whose production they have been employed. Maleic acid and malic acid may be recovered partly as such, but these acids, when used for making our new products, may also be recovered entirely or in part only as fumaric acid, which is a well known transformation product of each of those two acids.

We have described generally a continuous and continuing procedure from a mixture of glycerol and an acid or acids to the final water-resistant C-stage resin, but we wish it to be understood that either such a continuous or such discontinuous process can be used with equal satisfaction. That is, we may proceed from the glycerol and acids to either the A-stage or the B-stage and subsequently to the C-stage, or we may begin with an A-stage or B-stage resin and proceed to C-stage resin therefrom.

These resins all belong to the general class of plastics, and while we have specifically mentioned that they can be used to produce a molded article, it must be obvious to all that they are by no means restricted to such enumerated uses but can be used in many other places and in many other operations and for many other purposes where plastic materials can be used. It is also obvious that our invention includes these resins whether produced and used as such or whether produced in admixture or association with other ingredients. or used in admixture or association with other ingredients, and that the term resin as used in the claims is not to be construed as excluding the association or admixture of other ingredients with said resins.

We claim:

1. The process of making a resin which comprises heating a mixture containing a polybasic aliphatic carboxylic acid and a polyhydric alcohol between approximately 170 and 200 C. for about 20 hours. then below 135 C. for about 10 hours and finally at a higher temperature until a water-resist ant resin results.

2. The process of making a resin which comprises heating a mixture containing a polybasic aliphatic carboxylic acid and glycero between approximately 170 and 200 C. for about 20 hours, then below 135 C. for about 10 hours and finally at a higher temperature until a water-resistant resin results.

3. The process of making a resin which comprises heating a mixture containing a dibasic aliphatic carboxylic acid and a polyhydric alcohol until a water-resistant resin results.

4:. The process of making a resin which comprises heating a polybasic aliphatic carboxylic acid, an anhydride-forming aromatic dibasic carboxylic acid and a polyhydric alcohol until a water-resistant resin results.

5. The rocess of making a resin which comprises eating a polybasic aliphatic carboxylic acid, an anhydride-forming aromatic dibasic carboxylic acid and glycerol until a water-resistant resin results.

6. The process of making a resin which comprises heating a dibasic aliphatic carbox he acid, an anhydride-forming aromatic ibasiccarboxylic acid and a polyhydric alcohol until a water-resistant resin results.

7. The process of making a resin which comprises heating a dibasic aliphatic carboxylic acid, an anhydride-forming aromatic dibasic carboxylic acid and glycerol until a water-resistant resin results.

8. The rocess of making a resin which comprises eating fumaric acid and glycerol until a water-resistant resin results.

9. The process of making a resin which comprises heating a dibasic aliphatic carboxylic acid, a polynuclear aromatic carboxylic acid and a polyhydric alcohol until a water-resistant resin results.

10. The process of making a resin which comprises heating a polybasic aliphatic carboxylic acid, a polynuclear aromatic carboxylic acid and a polyhydric alcohol until a water-resistant resin results.

11. The process of making a resin which comprises heating a polybasic aliphatic carboxylic acid, a polynuclear aromatic carboxylic acid and glycerol until a water-resistant resin results.

12. A water-resistant resin such as can be obtained from a polynuclear aromatic carbox he acid, a polybasic aliphatic carboxylic aci and a polyhydric alcohol.

13. A water-resistant resin such as can be obtained from a polynuclear aromatic carbox lie acid, a polybasic aliphatic carboxylic aci and glycerol.

14. A water-resistant resin such as can be obtained from benzoyl-benzoic carboxylic acid, a polybasic aliphatic carboxylic acid and glyplero 15. a process of making a resin which comprises heatin a polybasic ahphatic carboxylic acid an a polyhydric alcohol between 170 C. and 200 C. until a product is obtained having a melting point between 90 C. and 120 0., heating this product between 90 C. and 200 C. until an infusiblc product is obtained, and heating said infusible product between 170 C. and 200 C. until a resin is obtained whose surface will not show a bloom when the resin is boiled in distilled water for two minutes.

16. The process of making a resin which comprises heatin a polybasie aliphatic carboxylic acid and a polyhydric alcohol between 170 C. and 200 C. until a product is obtained having a melting point between 90 C. and 120 0., heating this product between 90 C. and 135 C. until an infusible product is obtained, and heating said infusible product between 170 C. and 200 C. until a resin is obtained whose surface will not show a bloom when the resin is boiled in distilled water for two minutes.

17. A water-resistant polybasic aliphatic carboxylic acid-polyhydric alcohol resin.

18. A water-resistant (libasic, aliphatic carbox 'lic acid-polyhydric alcohol resin.

19. water-resistant glyccrol-fumaric acid resin.

20. A water-resistant resin such as can be obtained from a polybasic aliphatic carboxylic acid and glycerol.

21. A water-resistant resin such as can be obtained from a dibasic aromatic carboxylic acid, a polybasic aliphatic carboxylic acid and glycerol.

22. A water-resistant resin such as can be obtained from an aromatic carboxylic acid, a polybasic aliphatic carboxylic acid and a polyhydric alcohol.

23 A water-resistant resin such as can be obtained from an aromatic carboxylic acid, a dlibasic aliphatic carboxylic acid and glycero 24. A water-resistant resin such as can be obtained from a polynuclear aromatic carbox he acid, a dibasic aliphatic carboxylic aci and a polyhydric alcohol.

25. The process of making a resin which comprises heating a mixture containing an aliphatic dibasic carboxylic acid and glycerol between approximately 170 and 200 C. for about 20 hours, then below 135 C. for about 10 hours and finally at a higher temperature until a water-resistant resin results.

26. A water-resistant resin such as can be obtained from an aliphatic dibasic carboxylic acid and glycerol.

27. The process of making a resin which comprises heating a mixture containing fumaric acid and a polyhydric alcohol until a water-resistant resin results.

28. A water-resistant fumaric acid-polyhydric alcohol resin.

29. The process of making a resin which comprises eating fumaric acid, an anhydride-forniing aromatic dibasic carboxylic acid and a polyhydric alcohol until a waterresistant resin results.

30. A water-resistant resin such as can be obtained from fumaric acid, an auhydrideforming aromatic dibasic carboxylic acid and a polyhydric alcohol.

31. The process of making a resin which comprises heating fumaric acid, a polynuclear aromatic carboxylic acid and a polyhydric alcohol until a water-resistant resin results.

32. A water-resistant resin such as can be obtained from a polynuclcar aromatic carboxylic acid, fumaric acid and a polyhydric alcohol.

33. A water-resistant resin such as can be obtained from a polybasic aliphatic carboxylic acid, an anhydride-torming aromatic dibasic carboxylic acid and a polyhydric alcohol.

34. The process of making a resin which comprises heating an aromatic carboxylic acid, a polybasic aliphatic carboxylic acid, and a polyhydric alcohol until a water-resistant resin results.

35. A water-resistant resin such as can be obtained from a dibasic aliphatic carboxylic acid, an anhydride-forming aromatic dibasic carboxylic acid and a polyhydric alcohol.

36. A water-resistant resin such as can be obtained from a polybasic aliphatic can-boxylic acid, an anhydride-i'oruling aromatic dibasic carboxylic acid and g1 ycerol.

37. A water-resistant resin such as can be obtained from a dibasic aliphatic carboxylic acid, an anhydride-forming aromatic dibasic carboxylic acid and glycerol.

38. The process 0t making a resin which comprises heating; a dibasic aromatic carboxylic acid, a polybasic aliphatic carboxylic acid and glycerol until a water-resistant resin results.

39. The process of making a resin which comprises heating an aromatic carboxylic acid, a dibasic aliphatic carboxyiic acid and glycerol until a water-resistant resin results.

at). The process of making a resin which comprises heating a bcnzoyl-bcnzoic acid, a polybasic aliphatic carboxylic acid and glycerol until a water-resistant resin results.

41. The process of making a. resin which comprises heating a polybasic aliphatic carboxylic acid, a benzoyl-benzoic acid and a. polyhydric alcohol until a water-resistant resin results.

42. A water-resistant resin such as can be obtained from a benzoyl-benzoic acid, a polybasic ali hatic carboxylic acid and a polyhydric aiizohol.

43. The process of making a resin which comprises heating a polybasic aliphatic carboxylic acid, a henzoyl-benzoic acid and glycerol until a water-resistant resin results.

44. A water-resistant resin such as can be obtained from a benzoyl-benzoic acid, a polybasic aliphatic carboxylic acid and glycerol.

45. The process of making a resin which comprises heating a dibasic aliphatic carhoxylic acid, a benzoyl-benzoic acid and a polyhydric alcohol until a water-resistant resin results.

46. A water-resistant resin such as can be obtained from a benzoyl-benzoic acid, a dibasic aliphatic carboxylic acid and a polyhydric alcohol.

In testimony whereof we afiix our signatures.

CHARLES R. DOWNS. LOUIS WEISBERG.

CERTIFICATE OF CORRECTION.

Patent No. l, 667, 197.

Granted April 24, 1928, to

CHARLES R. DOWNS ET AL.

It is hereby certified that error the misspelled word "citirc" read out the word "carboxylic";

appears in the printed specification of the above numbered patent requiring correction as follows:

Page 2, line 22, for

"citric"; page 5, line 59, claim 14, strike and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 19th day of June, A. D. 1928.

(Seal) M. J. Moore, Acting Commissioner of Patents.

dride-forniing aromatic dibasic carboxylic acid and a polyhydric alcohol until a waterresistant resin results.

30. A water-resistant resin such as can be obtained from fumaric acid, an auhydrideforming aromatic dibasic carboxylic acid and a polyhydric alcohol.

31. The process of making a resin which comprises heating fumaric acid, a polynuclear aromatic carboxylic acid and a polyhydric alcohol until a water-resistant resin results.

32. A water-resistant resin such as can be obtained from a polynuclcar aromatic carboxylic acid, fumaric acid and a polyhydric alcohol.

33. A water-resistant resin such as can be obtained from a polybasic aliphatic carboxylic acid, an anhydride-torming aromatic dibasic carboxylic acid and a polyhydric alcohol.

34. The process of making a resin which comprises heating an aromatic carboxylic acid, a polybasic aliphatic carboxylic acid, and a polyhydric alcohol until a water-resistant resin results.

35. A water-resistant resin such as can be obtained from a dibasic aliphatic carboxylic acid, an anhydride-forming aromatic dibasic carboxylic acid and a polyhydric alcohol.

36. A water-resistant resin such as can be obtained from a polybasic aliphatic can-boxylic acid, an anhydride-i'oruling aromatic dibasic carboxylic acid and g1 ycerol.

37. A water-resistant resin such as can be obtained from a dibasic aliphatic carboxylic acid, an anhydride-forming aromatic dibasic carboxylic acid and glycerol.

38. The process 0t making a resin which comprises heating; a dibasic aromatic carboxylic acid, a polybasic aliphatic carboxylic acid and glycerol until a water-resistant resin results.

39. The process of making a resin which comprises heating an aromatic carboxylic acid, a dibasic aliphatic carboxyiic acid and glycerol until a water-resistant resin results.

at). The process of making a resin which comprises heating a bcnzoyl-bcnzoic acid, a polybasic aliphatic carboxylic acid and glycerol until a water-resistant resin results.

41. The process of making a. resin which comprises heating a polybasic aliphatic carboxylic acid, a benzoyl-benzoic acid and a. polyhydric alcohol until a water-resistant resin results.

42. A water-resistant resin such as can be obtained from a benzoyl-benzoic acid, a polybasic ali hatic carboxylic acid and a polyhydric aiizohol.

43. The process of making a resin which comprises heating a polybasic aliphatic carboxylic acid, a henzoyl-benzoic acid and glycerol until a water-resistant resin results.

44. A water-resistant resin such as can be obtained from a benzoyl-benzoic acid, a polybasic aliphatic carboxylic acid and glycerol.

45. The process of making a resin which comprises heating a dibasic aliphatic carhoxylic acid, a benzoyl-benzoic acid and a polyhydric alcohol until a water-resistant resin results.

46. A water-resistant resin such as can be obtained from a benzoyl-benzoic acid, a dibasic aliphatic carboxylic acid and a polyhydric alcohol.

In testimony whereof we afiix our signatures.

CHARLES R. DOWNS. LOUIS WEISBERG.

CERTIFICATE OF CORRECTION.

Patent No. l, 667, 197.

Granted April 24, 1928, to

CHARLES R. DOWNS ET AL.

It is hereby certified that error the misspelled word "citirc" read out the word "carboxylic";

appears in the printed specification of the above numbered patent requiring correction as follows:

Page 2, line 22, for

"citric"; page 5, line 59, claim 14, strike and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 19th day of June, A. D. 1928.

(Seal) M. J. Moore, Acting Commissioner of Patents. 

